Arcing tip and method for making the same



March 17, 1936. R ADAMS ARCING TIP R. l.. ADAMS y 2,034,550

ARCING TIP AND METHOD FOR MAKING THE SAME March 17, 1936.`

2 sheets-.Sheet 2 Filed Oct. 25, 1934 His Attorney.

Patented Mar. 17, 1936 UNITED STATES PATENT' OFFICE moms 'rrr AND Ms'rnon ron MAmNG m SAME Roy L. Adams, Schenectady, N. Y., assigner to General Electric Company, a corporation of New York `Application October 25, 1934, Serial No. 750,027

9 Claims.

5 to provide an efficient low cost arcing tip which has'a long life and is free from soldered joints. It is` a further objectof the invention to provide a simple method for manufacturing such' tips. Heretofore arcing tips generally -have been formed'by silver soldering a copper slug to two shaped pieces of tungsten impregnated with copper. The shaped pieces are soldered together at their end portions and form the contact surface ofthe arcing tip. In the manufacture of such tips powdered tungsten is pressed into similar slabs of desired shape which are then impregnated with molten copper in a manner well known in the art. The impregnated slabs are machined on all sides and rounded at their outer ends sov as to provide a substantially continuous contact surface jwhen mounted on the enciof the copper slug. The copper slug is machined to t closely against theV inner surface of the slabs and to form a continnation of the outer surfaces of the 'impregnated slabs when silver soldered thereto.' The manufacture of contacts of the abovetype is quite expensive owing to the large number of shaping, machining and soldering operations.

In-.accordance with the present invention the' arcing tip consists of a copper slug or supporting member which is formed by melting copper or like metal o'n to a contact portion which consists of a one-piece U-shaped member made of tung- *5 sten and impregnated withcopper or other metal of high electrical conductivity. vThis process involves no'brazing or soldering operations and re quires but one final machiningoperation.

The novel features which vare characteristic of L0 the present invention arev set forth with particularity in thegappended-claims. 'I'he invention however will best be understood from reference to the following' specification when considered in connection with the accompanying drawings in L5 which Fig. 1 is a. cross-sectional view of a mold and plunger for shaping powdered metal employed in the. fabrication of my improved arcing tip; Fig. 2 is a perspective view of the cold pressed I metal tip produced in the mold disclosed in Fig. 1; '0 Fig. 3 is a perspective view of a portion of a carbon boat with cold pressed metal pieces positioned therein; Fig'. liis a cross-sectional view on an enlarged scale of the apparatus'shown in Fig. 3,

, the cold pressed metal piecesbeing filled with 5 scrap copper for impregnation therewith; Fig. 5

-pressed metal pieces 3. The tip 'l thus formed is a perspective view of the coldtpressed metal after impregnation with copper; Fig. 6 is a. crosssectional view of a carbon boat and illustrates the-manner in whicha copper body or slug may be secured to the impregnated arcing tip, while 5 1 Fig. 7 is a perspective view of the completed arc- .bon boat 4 and separated by partitions 5, as indicated in Fig. 3. Pieces of scrap copper 6 are 15 placed within the pressed pieces 3, as indicated vin Fig. 4 of the drawings and the loaded carbon boat placed in a hydrogen furnace and the copper melted thereby thoroughly impregnating the 20 contains an amount of copper in excess of that required merely to impregnate the pressed'metal as clearly indicated in Fig. l5.

A plurlity'of tips thus formed, for convenience usually about six, are then placed in contact with one another and in alignment in a carbon boat 8. If it is desired to form a slot 9 in the upper end of the arcing tip, a graphite bar I0 may be positioned in the boat 8 above the shaped impregnated pieces l as indicated in Fig. 6. The boat is then filled with scrap copper Il, as in' V dicated in Fig. 6, and the loaded boat placed in a hydrogen furnace and the copper melted. The molten 'copper penetrates into the tungsten impregnated pieces 'l and between the adjacent tirely free fromsoldered joints or the like.

The long arcing tip thus formed is machined to provide it with a suitable finish and to remove excess copper from the lower portion thereof. Faint lines indicate the junction between the several tips employed; in the fabrication oi the single tip and the tip is cut along these lines to provide forexample six arcing tips IZ, as `indicated in Fig. 7. 'I'he tips thus formed may be providedwith screw-threaded openings 'I3 for attachment to any suitable supporting means. i

What I claim as new and desire to secure by vLettersPaten't of the United States, is:

35 pieces forming one long integral arcing tip en- 2. The-method of making an arcing tip which comprises pressing tungsten into a desired shape, L

impregnating'the shaped member with an excess of copper and applying molten copper to said impregnated member to provide a support therefor.

3. The method of making an arcing tip which comprises pressing a refractory metal into a desired. shape, impregnating the shaped member with a metal of high electrical conductivity and applying' molten metal of high electrical Aconducthereby provide a support for said impregnatedl pieces.

5. The method of making an arcing tip which comprises applying molten metal of high electrical conductivity to a shaped metal piece consisting substantially of tungsten and copper toY provide a support therefor. i

6. An arcing tip consisting of a U-shaped conaosauno tact member and a body portion, said contact member consisting substantially of tungsten and copper, said body portion being .formed by applying molten copper to said contact member.

7. An arcing tip' comprising a contact portion anda supporting portion therefor, said contact portion comprising a one-piece U-shaped member consisting of tungsten particles impregnated with copper, said supporting member consisting substantially of pure copper cast on to said contact portion, said arcing tip being free from brazed or soldered joints. i

8. Anarcing tip comprising a one-piece con? tact portion and a supporting portionintegi'liy joined thereto, said tip being free from b'azed or soldered joints, said contact portion consisting substantially of tungsten and copper.

9. The method of making an arcing tip consist ing of a body portion and a contact portion which comprises pressing powdered tungsten into a U- shaped member, applying suiiicient molten copper to said shaped tungsten member to impregnate the pores thereof and provide a body po r"4 tion of substantially pure copper integral' Owith said shaped member, and machining saida'rcing tip to remove excess copper'from the surface of 

